A flow meter of the type mentioned at the outset is described in WO 2014/006001 A1. In the case of known embodiment, the measurement casing is inserted into a recess of the sensor casing, wherein the outer contour of the measurement casing and the recess are configured essentially rectangular-shaped. Consequently, a rotation of the sensor casing is prevented in the circumferential direction relative to the measurement casing. A readjustment of the sensor casing in the circumferential direction with a permanently installed measurement casing is thus not possible.
DE 102 49 566 A1 relates to a flow meter, which responds differently to forward and reverse flows. The flow meter has a two-part housing. Its inlet-side housing part is designed in tubular fashion and is fitted with a tube extension in a corresponding intake area of a second output-side housing part. For sealing between the housing parts, the first housing part is provided with annular grooves that open outwardly in a radial manner, which are located in the O-rings.
WO 2008/105330 A1 relates to a flow meter with two tubular housing parts, wherein an impeller is arranged in the first housing part. Each of the housing parts has a connection for a pipe at the end. The housing parts can be connected to one another, whereby a seal is provided between the housing parts.
EP 2 154 490 A1 relates to a flow meter for liquids with a measurement casing with a first connection and a second connection, whereby a sensor casing is coupled firmly to the measurement casing.
To this end, the present invention is based on the task of further developing a flow meter of the type mentioned at the outset in such a way that the assembly of the measurement casing and of the sensor casing is simplified.
According to the invention, the object is achieved as described below.
The measurement casing is designed as a measuring tube and has a closed cylindrical surface, wherein the sensor casing has a recess adapted to the cylindrical surface and is arranged coaxially with the measurement casing and can be swivelled in the circumferential directions.
The embodiment, according to the invention, is distinguished from the state of the art in that the measurement casing can be installed in a measuring position in any desired angular position, since the sensor casing can be rotated on the permanently mounted measurement casing, even later in a position, which is, for example, used for reading a display unit. The sensor casing can be mounted on the measuring tube, independent of the angular position of the measuring tube and fixed in any desired angular position.
The fixing of the sensor casing preferably takes place by means of a clamping element in any angular position relative to the circumferential direction of the measurement casing.
In order to prevent the movement of the sensor casing in axial direction of the measurement casing, it is provided that the cylindrical surface area of the measurement casing is limited in axial direction by the limiting means such as circumferential flanges. The flanges can fit closely at the side walls of the sensor casing or the side walls can have slots, which accommodate the circumferential flanges.
In order to achieve an optimum signal transmission on the one hand and a high stability on the other, it is provided that a wall thickness of the cylindrical surface area of the measuring tube is conical, whereby a wall of the measuring tube has a smaller wall thickness in the area of the measuring unit than in the area of the circumferential flanges.
According to a further preferred embodiment, it is provided that the sensor casing has a measuring window in the area of the sensor, which is designed as a recess or as a section with low wall thickness.
The wall of the measuring tube and the measuring window of the sensor casing are made of a material, which is permeable to electromagnetic radiation.
In order to achieve a close coupling between the cylindrical surface area of the measuring tube and the inner wall of the sensor casing, it is foreseen that a surface of the recess of the sensor casing facing the cylindrical surface area is matched to a contour of the surface area of the measurement casing.
According to a further preferred embodiment, it is provided that the flow meter is designed as a compact flow meter, that is to say, an evaluation electronics, a display unit with operating elements and/or a power supply is arranged in the sensor casing, in addition to the sensor. Said sensor casing thus assumes the function of a transmitter for the non-contacting and cordless detection of a flow of liquids through the measuring tube.
In order to achieve a compact design, the sensor is arranged on a support, such as a circuit board, which is detachably arranged in the sensor casing.
Preferably, the sensor is arranged on a lower side of the support facing the measuring unit in the area of the measuring window.
The sensor is preferably designed as a reed contact, which detects the rotation of the measuring unit, which is preferably embodied as a magnet.
Further details, advantages and features of the invention result not only from the claims that can be had from the characteristics—for themselves and/or in combination—but also from the following description of a preferred exemplary embodiment to be taken from the drawings.